JPS6016566B2 - gas sampling probe - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a gas sampling probe used to sample various gases such as NH3, N02, S02, etc., which cause moisture condensation, ammonium salt formation, etc. due to temperature drop.

Conventionally, various gas sampling probes having sampling tubes protruding into gas flow passages have been used to sample high-temperature gases such as exhaust gas from boilers, heating furnaces, etc., reaction gases, etc. from the gas flow passages.

However, in these probes, the sampling tube is not heated, so the temperature of the sample gas decreases in the sampling tube, resulting in condensation of water in the sample gas, dissolution of gas components in the condensed water, and formation of bases. This method has the disadvantage that salts are formed due to the reaction between the acidic components and the acidic components, and the concentration of the sampled gas components is lower than the actual value. Therefore, as a result of various studies on heating methods for sampling tubes, the present inventors found that
We have found that the most preferable method is to make the sampling tube from a conductive material and heat it with Joule heat by applying electricity to both ends of the sampling tube, and based on this knowledge, we have completed the present invention.

Hereinafter, the present invention will be explained based on the drawings.

FIG. 1 is a longitudinal sectional view of one embodiment of the present invention, and FIG. 2 is a longitudinal sectional view of another example of the sampling tube.

In the figure, 1 is the sampling tube, 2 is the side wall of the gas flow passage, 5,
7 is a heat-resistant electrically insulating sealing material, 6 is an electrically insulating material, 1
1 is a gas flow path, and 21 is a power supply section. In FIG. 1, the sampling tube 1 is made of a conductive material that itself has corrosion resistance against the sample gas and generates heat when energized.

As such materials, metals such as titanium and titanium alloys are used when used in a high temperature atmosphere, and conductive Teflon, conductive rubber, conductive resin, etc. are used when used at low temperatures. The sampling tube 1 has an outer tube 15 having a flange at one end 17, and an inner tube 13 is inserted into the outer tube 15 with a gap therebetween.
Although the tip 12 is integrated into a double-tubular structure by forming a spiral shape, it is preferable to make the tip part, where the temperature drop is relatively large, thinner than the other parts. sampling tube 1
First, in order to electrically insulate and fix the sampling tube 1 to the side wall 2 of the gas flow passage 11, a gap is provided between the tip 12 of the sampling tube 1 and the side pipe 3 provided on the side wall 2 of the gas flow passage 11. will be inserted.

Next, the collar 16 of the other rear end of the sampling tube 1 and the side tube 3
An electrically insulating sealing material 5 is inserted between the collar 4 at the end, and an electrically insulating material 6 is inserted between the collars 16 and 17 at the end of the sampling tube 1. Then, the collar 8 at the end of the sample gas outlet tube 10 is placed on the upper surface of the collar 17 at the end of the sampling tube 1 via the electrically insulating sealing material 7, and the bolt is connected between it and the collar 4 of the side tube. The sampling tube is attached and insulated by tying at step 9. As the electrically insulating sealing materials 5 and 7 and the electrically insulating material 6, sheets, laminates, or molded products of vulcanized fiber, asbestos, Teflon, rubber, etc. are used.

The power supply section 21 is for supplying electricity to the collars 16 and 17 at the rear end of the sampling tube 1 through lead wires 18 and 19, and is composed of a transformer 22 and an input controller 23.

The transformer 22 is desirably one that can supply a low voltage of about 0.5 to 10 V and a large current of about 10 to 100 A to facilitate insulation of the sampling tube 1. Input controller 2
3 is for controlling the input to the transformer 22 by the output of the side warmer 14 such as a thermocouple, resistance side warmer, thermistor, etc. provided in the sampling tube 1, and an on/off controller etc. is used. It will be done. Both are connected by a lead wire 20.
Incidentally, the sampling tube 1 may have a shape in which a flange is provided at one end 17 of the tube, as shown in FIG. 2.

In this case, the lead wire 18 may be connected to the end l6 of the tip 12, and the lead wire 18 may be passed through the electrically insulating sealing material 5 and drawn out of the side wall 2. The temperature of the sampling tube 1 can be adjusted to a temperature of 50 to 50°C, which is the same as or higher than that of the gas flow path 11, by appropriately selecting the current flowing through the flanges 16 and 17 at both ends of the sampling tube 1, the material and thickness of the sampling tube 1.
It is heated and maintained at an arbitrary predetermined temperature within a range of about 400 qo.

The gas in the gas flow passage 11 is transferred to the tip 1 of the sampling tube 1.
The sample gas passes through the tube from 2 and is supplied to a measuring device (not shown) via a sample gas outlet tube 10. As described in detail above, the device of the present invention directly energizes the sampling tube 1 and causes the sampling tube 1 itself to generate heat using Joule heat, so the device is not only simple but also capable of controlling the temperature to a predetermined uniform temperature. It has many advantages such as being easy.

Therefore, it is particularly useful as a device for continuously or intermittently collecting samples from flue gas.

[Brief explanation of the drawing]

FIG. 1 is a longitudinal sectional view of one embodiment of the present invention, and FIG. 2 is a longitudinal sectional view of another example of the sampling tube. 1: Sampling pipe, 2: Side wall of exhaust gas flow path, 5, 7
: electrically insulating sealing material, 6: electrically insulating material, 11: gas flow path, 21: power supply section. Figure 1 Figure 2

Claims (1)

[Claims] 1. A sampling tube made of a conductive material, a mounting means for causing the tip of the sampling tube to protrude inward from the side wall of the gas flow path to be sampled, and for fixing the tip of the sampling tube in an electrically insulated manner from the side wall; A gas sampling probe consisting of a power supply section that conducts electricity.